Sheet metal and other workpieces can be fabricated into a wide range of useful products. The fabrication (i.e., manufacturing) processes commonly employed involve bending, folding, and/or forming holes in the sheet metal and other workpieces. The equipment used for such processes involve many types, including turret presses and other industrial presses (such as single-station presses), Trumpf style machines and other rail type systems, press brakes, sheet feed systems, coil feed systems, and other types of fabrication equipment adapted for punching or pressing sheet materials.
Concerning press brakes, they are equipped with a lower table and an upper table, and are commonly used for deforming metal workpieces. One of the tables (typically the upper table) is configured to be vertically movable toward the other table. Forming tools are mounted to the tables so that when one table is brought toward the other, a workpiece positioned there between can be formed, e.g., bent into an appropriate shape. Typically, the upper table holds a male forming tool (a punch) having a bottom workpiece-deforming surface (such as a V-shaped surface), and the bottom table holds an appropriately-shaped female tool (a die) having an upper surface vertically aligned with the workpiece-deforming surface of the male tool.
As is known, the forming tools are commonly mounted to press brake tables via use of one or more tool holders provided on the tables. Particularly, tangs or shanks of the tools are inserted between opposing portions of the holder that define a channel. Quite often, the channel is defined via a stationary portion of a first wall and a movable portion of an opposing second wall of the tool holder. As forming tools are available in a variety of shapes and sizes, the tangs for the tools also vary, particularly with regard to their profiles. One tang type (generally known as American style) has smooth, straight vertical sides extending upward from the tool body, and upon which the opposing portions of a tool holder contact when the tang is loaded there between. Other tang types (generally known as European or precision styles) have one or more grooves defined in their vertical sides, which in some cases are used in self-seating the tools when they are loaded between and subsequently contacted by the opposing portions of the tool holder.
Each tang style offers its own specific advantages. For instance, in utilizing straight style tangs, tooling is often found to be relatively easy to load and remove from tool holders, and more easily accommodated by differing makes of tool holders. On the other hand, in utilizing grooved style tangs, tooling can be more precisely held by tool holders (via seating mechanisms) so as to machine workpieces with high degree of accuracy. Traditionally, tool holders were designed to accommodate only one style of tool tang. However, this correspondingly limited the various tooling that could be used with such holders. Thus, the press brake industry started seeing the introduction of tool holder designs capable of being used with tools having different tang styles. However, such designs have not been without drawbacks.
For example, many of these tool holders have been designed to function with adaptors in accommodating different tang styles. With some designs, the adaptors dictate being changed out (in the case of multiple adaptors) or reoriented (in the case of a single adaptor) to accommodate the different tang styles. Unfortunately, the need for orienting the adaptor not only leads to corresponding downtime for the machine, but also introduces risk of improper orientation and corresponding production errors. Conversely, in other perhaps more conventional tool holder designs, instead of varying orientation of adaptors to accommodate different tang styles, the adaptors are held in a set orientation, and moved inwardly toward the tool tangs at different distances corresponding to the tang styles. However, such differing movements, and corresponding variances in force applied to accommodate such movements, typically dictates precise regulation of the force, or else damage can result to the tangs and/or the tool holders from contact there between. Such regulation has conventionally been provided via hydraulic, pneumatic, electric, or other like means, whereby the applied forces can be precisely administered, although incorporation of these elements adds complexity and overall cost to the designs.
One variable not yet described but given consideration in the design of tool holders is built-in tolerance. For example, there is generally a slight degree of variance with each tool and tool holder design, such as relating to general dimensions of the tool (e.g., its tang) or to actions of the tool holder (e.g., closing action(s) of one or more movable portions of the holder). By themselves, these variances can be deemed fairly negligible; however, they can present issues when encountered collectively, such as in the circumstance of loading forming tools in tool holders. For example, such variances can result in a corresponding degree of play for the tooling once loaded into the tool holders. To account for such variances, areas of tolerance have been provided in the tool holder designs. For example, tool holders have often been equipped with shape memory materials or structures such as springs to provide such areas of tolerance within the designs. However, even with the addition of such elements, issues of looseness or play between tool and holder can still be found to exist.
Thus, there remains a need for a tool holder design that accounts for the above-described issues as well as others, and in so doing to provide both an effective and efficient tool holder usable with tools having different tang styles.